US6138397A - Method and device for operation of a trawl - Google Patents

Method and device for operation of a trawl Download PDF

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Publication number
US6138397A
US6138397A US09/194,837 US19483799A US6138397A US 6138397 A US6138397 A US 6138397A US 19483799 A US19483799 A US 19483799A US 6138397 A US6138397 A US 6138397A
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United States
Prior art keywords
trawl
trawls
vessel
cables
cable
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Expired - Lifetime
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US09/194,837
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English (en)
Inventor
Helge Hammersland
Arne Tvedt
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Scantrol AS
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Scantrol AS
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    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01K—ANIMAL HUSBANDRY; AVICULTURE; APICULTURE; PISCICULTURE; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
    • A01K73/00—Drawn nets
    • A01K73/02—Trawling nets
    • A01K73/04—Devices for spreading or positioning, e.g. control thereof

Definitions

  • the present invention relates to a process and an arrangement for operation of a trawl, that is to say to control the movements for a trawl for fishing, as is indicated in the introduction to the following process and arrangement claims, together with an application thereof.
  • the invention has to do with being able to control and optimise the position of the trawl at seas so that fishing is made efficient.
  • the invention especially has to do with the operation of bottom trawls.
  • a trawl comprises a cornet-shaped bag of a net material open at the front and closed at the rear.
  • the front part of the trawl constitutes a funnel-shaped guide portion which conducts or controls the catch of fish, shrimps and the like backwards and into the rear portion which constitutes the trawl bag per se in which the catch is collected.
  • a number of cables such as wires or chain links connect the trawl with a fishing vessel (a trawler).
  • Each cable comprises extension means such as a trawl door (a paravane) for stretching out the front portion of the trawl, that is to say the entrance portion to the trawl bag. Rearmost the trawl bag can be opened in order to empty out the catch, for example when the trawl is hauled up on the deck of the vessel.
  • the trawl control systems which are employed to-day control the trawl by maintaining equal tension in the cables which pull the trawl. This is done in practice by maintaining equal tension force on the winch motors.
  • an optimum trawl geometry is meant that the trawl bag is adjusted approximately symmetrically about a vertical plane through the longitudinal axis of the trawl.
  • the direction of flow of the water into the opening portion of the trawl is approximately at right angles to a plane at right angles to the longitudinal axis of the trawl it is reckoned that the trawl has an optimum adjustment relative to the direction of flow of the water for the achievement of the most effective fishing.
  • the trawl geometry during towing deviates from the optimum, the trawl fishes poorer, and it can become unstable.
  • the trawls are to be designed differently depending upon what type of fish it shall fish, and by the size of the vessel.
  • the trawl producers indicate what opening the trawl must have (height and breadth), and this is designated as the optimum entrance opening for the trawl.
  • the trawl doors When the trawl is towed over an oblique sea bottom, as is shown in FIG. 4a, the trawl doors shall be at different depths, that is to say both the trawl doors shall have bottom contact. If the cable tension in the two cables is the same one risks the lowermost trawl door 24 losing the bottom contact. In that case the force of friction becomes equal to zero, and the associated winch will draw in cable 14 until the tension in this becomes equal to the tension in the other cable 16. With that the trawl 12 becomes obliquely positioned, and can completely lose contact with the sea bottom.
  • sensors can be mounted for measuring the quantity of fish both in the entrance portion of the trawl an within the trawl bag itself, and for measuring the height of the entrance opening of the trawl an its speed through the sea.
  • These systems/sensors have however no connection with the control system of the trawl/winch, but are employed exclusively by the skipper of the vessel for assessing how much engine power has to be used, and how much fish lies in the trawl, possibly also to check that the trawl/trawl bag is not damaged.
  • FIG. 1 shows schematically a vessel which tows a trawl after itself.
  • FIG. 2 shows a flow diagram of the coupling up of the control system according to the invention.
  • FIG. 3 shows a tow situation where the control system according to the invention is used.
  • FIG. 4 shows the vessel schematically and where the trawl is towed along the sea bottom. More specifically FIG. 4a shows the situation according to the previously known technique (discussed earlier). FIG. 4b shows the situation where the control system according to the invention is used.
  • FIG. 5 shows a towing situation where the control system according to the invention is used during a common tow of two trawls situated in parallel.
  • FIGS. 1 and 2 illustrate a vessel 10 which tows a trawl 12 after itself.
  • the rearmost of the trawl comprises the trawl bag 13 itself in which the fish are collected.
  • the surface of the sea is illustrated at 11.
  • the trawl 12 is mounted in winches of the vessel 10 (a winch 26 is shown in FIG. 2) via two cables 14,16, and these are fastened to the trawl on each side of its entrance portion 18.
  • the trawl entrance opening comprises stretching means, such as weights, for example lead lines in the bottom and buoyancy means in the upper part, for contributing to maintaining the opening portion stretched out.
  • a trawl can besides have varying opening diameters (18) of from 5-6 meters and up to 30-40 meters.
  • trawl door (a paravane) 22 and 24 respectively just before the opening 18 and the trawl doors feather during the towing out to each side so that the entrance opening 18 of the trawl 12 is held stretched out.
  • trawl 12 can be situated so deep that it sweeps the sea bottom. It will be apparent that the cables between trawl doors and trawl form a fan shape.
  • a sensor 30 or equivalent which in use can continuously record the current conditions in the form of the direction of the flow of water, in the ocean in the region adjacent to the trawl.
  • the sensor 30, for example of the SCANMAR S4TSS type, is especially adapted for measuring the direction and speed of the sea and in towards opening 18 of the trawl.
  • the current measurer 30 is positioned (is fixed) preferably directly to the upper side of the trawl, adjacent to the opening 18, also called "the head line".
  • the head line can comprise a rope or a wire which passes around the periphery to the entrance opening of the trawl.
  • the sensor 30 is adapted to both record the current conditions, plus to transmit data to a receiver in the vessel.
  • the signals can be transmitted to the vessel by wireless and/or through a separate cable.
  • a hydrophone 32 (of the SCANMAR type or equivalent), which (wireless) can receive the records when these are transmitted from the sensor 30 in the form of sound waves, indicated at 28 and 29 on FIG. 2. Both the sensor and hydrophone instruments are commercially available.
  • the signals which are recorded by the hydrophone are transmitted through a cable (wire) 33 to a receiver unit 34, for example a signal converter of the SCANMAR RU400 type or the like in a control room (wheel house) on board and which decodes the signals.
  • the signals are transmitted to a computer (36SCANTROL AC 501 or the like) through cable 37.
  • the computer 36 is further coupled up via cables (wires) 41 to the two winches of which only one is shown at 26 in FIG. 2. In the invention it is the direction of flow P3 of the sea in towards the sensor 30, which is regulating parameter.
  • the program will include the winches being controlled so that the deviation from the optimum trawl adjustment becomes as small as possible, in that the sensor records the direction of the flow of water relative to a given standard (desirable) direction, based on the construction and geometry of the trawl in the outstretched position.
  • the information which is received from the sensor 30 is employed as follows:
  • each of the winches 26, that is to say the adjustment of their tension force is regulated individually via the compute 36 so that the trawl opening 18 is set the whole time in the optimum direction, that is to say that the water flow has a direction directly into the opening 18. Then the trawl is defined as stable.
  • the current conditions (plus the speed) is measured and registered in a time period of 3-5 minutes.
  • steps 1-3 are repeated at regular intervals. This process can also be carried out continuously and automatically.
  • Optimum size of the entrance opening, correct trawl geometry and a stable trawl are obtained totally independent of friction in the winch and in blocks, and independently of problems with accurate rigging.
  • rigging is meant the design and the length of the cables which extend between trawl and trawl doors.
  • Further correct trawl geometry and stable trawls are achieved in varying current conditions at the sea bottom and at the surface, and in varying weather conditions. Further correct trawl geometry and stable trawls are obtained on fishing in obliquely shaped bottoms (see FIG. 4) since good bottom contact is achieved and the loss of fish beneath the trawl is avoided.
  • FIGS. 3-5 there are shown a series of situations which arise during active fishing with trawl equipment, and illustrate how a trawl will perform on using the previously known solutions (also discussed in part above), and on using the present invention.
  • FIG. 3 shows a typical towing situation where the trawler vessel moves forwards in the sea at a given speed in the direction of the arrow P1.
  • the trawl itself lies in the sea at a given depth beneath the ocean surface 11.
  • the ocean current on the spot, at the depth of the trawl, is shown at P2.
  • the resulting current of water, relative to the trawl, is shown with P3.
  • the tension force of the trawl winches are regulated on board so that the opening of the trawl becomes optimum, that is to say that the trawl is adapted so that the current P3 goes as far as possible in the right direction towards the trawl opening.
  • An optimum trawl opening comprises that the direction of flow P3 of the water is approximately at right angles to a plane at right angles to the longitudinal direction/axis of the trawls. It is this direction of flow P3 which is sensed by the sensor 30. The current will then give via the outward stretching of the trawl doors 22,24 optimum opening.
  • the lowermost trawl door 24 can thereby lose the bottom contact. In that case the force of friction becomes zero, and the associated winch will draw in wire 14 until the tension in this becomes equal to the tension in the other wire 16.
  • the trawl 12 becomes obliquely disposed, and can lose contact with the bottom. The fish catch can thus be lost.
  • FIG. 5 there is shown how the control system according to the invention is applied when the vessel tows two trawls 40,42 disposed essentially in parallel.
  • two trawls having a length of 102 meters, a vertical entrance opening height of 11 meters, horizontal breadth 25 meters, and where the horizontal distance between front portions of the bags is also 25 meters.
  • the outer sides of the trawls are connected to their respective winches on board the vessel via cables 44,46 having trawl doors/paravanes 22,24 mounted on.
  • the mutually adjacent bag sides are connected or bound together with wires 48,50 (each anchored to the trawl so that a fan shape is formed) at a point which comprises a heavy body or weights in the form of lead 52, which can prevent the third towing cable 45 from lifting the trawls from the bottom.
  • the third towing cable 45 extends forwards to a third winch on board the vessel.
  • the tension in the three wires is designated FW1, FW2 and FW3.
  • Such a double trawl arrangement will render effective the fishing strongly in relation to necessary towing energy, and has therefore had an increasing application within trawl fishing.
  • the centre wire 45 is regulated so that it has a fixed length difference relative to the length for the outer wires 44,46.
  • the wire tension FW3 regulates so that it has a fixed tension relationship relative to the two outer tensions FW1, FW2.
  • such a double trawl system can now be controlled by arranging a current direction sensor 60 of the type which is explained above in the upper side of the one of the trawls 40,42 or that the trawls each comprise their respective separately acting sensor.
  • the tension in the winches is regulated then based on what the sensors record.
  • the control system is adapted then so that the length of the centre wire 45 is regulated until the water flow comes directly into the trawl opening(s). Thereby it is unnecessary to find the correct length difference/tension relationship as described above, and such as was previously usual.
  • each trawl comprises a sensor
  • the signals from these are combined in the control system of the vessel, and the tension force in all three cables 44,45,46 is regulated so that both the trawls are adjusted in an optimum position for an effective catch.

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  • Life Sciences & Earth Sciences (AREA)
  • Environmental Sciences (AREA)
  • Animal Husbandry (AREA)
  • Biodiversity & Conservation Biology (AREA)
  • Farming Of Fish And Shellfish (AREA)
  • Other Liquid Machine Or Engine Such As Wave Power Use (AREA)
US09/194,837 1996-06-03 1997-06-02 Method and device for operation of a trawl Expired - Lifetime US6138397A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
NO962273 1996-06-03
NO962273A NO302391B1 (no) 1996-06-03 1996-06-03 Fremgangsmåte og anordning ved tråldrift og anvendelse derav
PCT/NO1997/000136 WO1997046087A1 (en) 1996-06-03 1997-06-02 Method and device for operation of a trawl

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US6138397A true US6138397A (en) 2000-10-31

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US09/194,837 Expired - Lifetime US6138397A (en) 1996-06-03 1997-06-02 Method and device for operation of a trawl

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US (1) US6138397A (da)
EP (1) EP0959676B1 (da)
AU (1) AU3109097A (da)
DE (1) DE69714863D1 (da)
DK (1) DK0959676T3 (da)
ES (1) ES2182091T3 (da)
IS (1) IS1879B (da)
NO (1) NO302391B1 (da)
NZ (1) NZ333103A (da)
PT (1) PT959676E (da)
WO (1) WO1997046087A1 (da)

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6312301B1 (en) * 2000-09-15 2001-11-06 Lawrence R. Kennedy Virtual slalom course
US6505573B1 (en) 2001-07-12 2003-01-14 Sherwin Sheikholeslam Towrope retriever for watercraft
US20050087119A1 (en) * 2002-01-16 2005-04-28 Roar Pedersen Trawling vessel with a lock chamber
WO2005055709A1 (en) 2003-12-09 2005-06-23 Henning Skjold-Larsen Sensor module for trawl
US20050160656A1 (en) * 2002-03-22 2005-07-28 Safwat Sheriff A. Self-spreading trawls having a high aspect ratio mouth opening
WO2006067555A1 (en) 2004-12-21 2006-06-29 Maquet Critical Care Ab Liquid dosing arrangement
US7487614B1 (en) * 2005-01-27 2009-02-10 Seth Walker Radio controlled gill net recovery transmitters
US20090133313A1 (en) * 2006-08-08 2009-05-28 Henning Skjold-Larsen Angle-Based Filling Ratio Indicator
US20090282723A1 (en) * 2006-08-31 2009-11-19 National University Corporation Tokyo University Of Marine Science And Technology Trawl net layer-by-layer collecting device
US20100114381A1 (en) * 2004-08-06 2010-05-06 Welch John M Towrope Winch User Interface
US20100211239A1 (en) * 2004-08-06 2010-08-19 Christensen Ladd E Towrope Winch Dead Start
US20100224117A1 (en) * 2004-08-06 2010-09-09 Global Innovative Sports Incorporated Towrope Winch Safety Shutoff Switch
US8757079B2 (en) 2004-08-06 2014-06-24 Global Innovative Sports Incorporated Winch system safety device controlled by towrope angle
US20140259864A1 (en) * 2013-03-13 2014-09-18 Kalapa Bvba Fish-sorting system for sorting fish in a dragged fishing net
US20140373425A1 (en) * 2011-09-22 2014-12-25 Scantrawl As System and method for controlling and displaying parameters during trawling
US20150135835A1 (en) * 2012-05-16 2015-05-21 Scantrawl As Twin trawl geometry
US20150156998A1 (en) * 2013-12-09 2015-06-11 Smart Catch LLC System, method, and platform for remote sensing and device manipulation in fishing environments
US20150272094A1 (en) * 2014-04-01 2015-10-01 Lawrence Ahlfert Pearlman "Smart" Semi-Autonomous Trawler Fishing Net
US9592890B2 (en) 2004-08-06 2017-03-14 Global Innovative Sports Incorporated Towrope winch rider profile
US9968824B2 (en) 2006-08-10 2018-05-15 Exerciting, Llc Exercise device providing user defined pedal movements
US11382318B2 (en) * 2017-07-24 2022-07-12 Stø Technology As System, apparatus, and method for trawl handling
EP4066634A1 (en) * 2021-03-23 2022-10-05 Volu Ventis ApS Controllable trawl doors and a method for controlling the same

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NO343812B1 (en) * 2017-04-07 2019-06-11 Remoey Sea Group As Arrangement for manoeuvring a boat
CN110301406A (zh) * 2019-05-17 2019-10-08 浙江省海洋水产研究所 一种可监控及统计捕捞产量的智能拖网

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU134162A1 (ru) * 1959-11-04 1959-11-30 Л.К. Пугачев Спусковой механизм к охотничьим ружь м
SU685255A1 (ru) * 1977-04-18 1979-09-15 Специальное Экспериментально-Конструкторское Бюро Промышленного Рыболовства Устройство дл определени перекоса рыболовного трала
SU713553A1 (ru) * 1977-08-24 1980-02-05 Khromov Viktor A Способ определени перекоса трала
US4246781A (en) * 1978-04-04 1981-01-27 Kaarbos Mek. Verksted A/S Arrangements for measuring tension loading in wires
US4305571A (en) * 1977-02-01 1981-12-15 Karmoy Mekaniske Verksted A/S Means for regulating two trawl winches
SU1308305A1 (ru) * 1984-09-07 1987-05-07 Научно-Производственное Объединение По Технике Промышленного Рыболовства Устройство дл определени перекоса трала
US5099458A (en) * 1988-09-05 1992-03-24 Furuno Electric Co., Ltd. Underwater detection system
GB2266694A (en) * 1992-05-06 1993-11-10 Karmoy Winch As Controlling trawler cable tension
US5347860A (en) * 1993-09-21 1994-09-20 Rimer J Patton Benthic sampling effectiveness measurer

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU134162A1 (ru) * 1959-11-04 1959-11-30 Л.К. Пугачев Спусковой механизм к охотничьим ружь м
US4305571A (en) * 1977-02-01 1981-12-15 Karmoy Mekaniske Verksted A/S Means for regulating two trawl winches
SU685255A1 (ru) * 1977-04-18 1979-09-15 Специальное Экспериментально-Конструкторское Бюро Промышленного Рыболовства Устройство дл определени перекоса рыболовного трала
SU713553A1 (ru) * 1977-08-24 1980-02-05 Khromov Viktor A Способ определени перекоса трала
US4246781A (en) * 1978-04-04 1981-01-27 Kaarbos Mek. Verksted A/S Arrangements for measuring tension loading in wires
SU1308305A1 (ru) * 1984-09-07 1987-05-07 Научно-Производственное Объединение По Технике Промышленного Рыболовства Устройство дл определени перекоса трала
US5099458A (en) * 1988-09-05 1992-03-24 Furuno Electric Co., Ltd. Underwater detection system
GB2266694A (en) * 1992-05-06 1993-11-10 Karmoy Winch As Controlling trawler cable tension
US5347860A (en) * 1993-09-21 1994-09-20 Rimer J Patton Benthic sampling effectiveness measurer

Cited By (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6312301B1 (en) * 2000-09-15 2001-11-06 Lawrence R. Kennedy Virtual slalom course
US6505573B1 (en) 2001-07-12 2003-01-14 Sherwin Sheikholeslam Towrope retriever for watercraft
US6672238B2 (en) 2001-07-12 2004-01-06 Sherwin Sheikholeslam Towrope retriever for watercraft
US20050087119A1 (en) * 2002-01-16 2005-04-28 Roar Pedersen Trawling vessel with a lock chamber
US7165502B2 (en) 2002-01-16 2007-01-23 Sintef Fiskeri havbruk AS Trawling vessel with a lock chamber
US20050160656A1 (en) * 2002-03-22 2005-07-28 Safwat Sheriff A. Self-spreading trawls having a high aspect ratio mouth opening
US7405999B2 (en) 2003-12-09 2008-07-29 Henning Skjold-Larsen Sensor module for trawl
WO2005055709A1 (en) 2003-12-09 2005-06-23 Henning Skjold-Larsen Sensor module for trawl
US20070089349A1 (en) * 2003-12-09 2007-04-26 Henning Skjold-Larsen Sensor module for trawl
US20100211239A1 (en) * 2004-08-06 2010-08-19 Christensen Ladd E Towrope Winch Dead Start
US20100224117A1 (en) * 2004-08-06 2010-09-09 Global Innovative Sports Incorporated Towrope Winch Safety Shutoff Switch
US9592890B2 (en) 2004-08-06 2017-03-14 Global Innovative Sports Incorporated Towrope winch rider profile
US8757079B2 (en) 2004-08-06 2014-06-24 Global Innovative Sports Incorporated Winch system safety device controlled by towrope angle
US20100114381A1 (en) * 2004-08-06 2010-05-06 Welch John M Towrope Winch User Interface
US8651461B2 (en) 2004-08-06 2014-02-18 Global Innovative Sports Incorporated Towrope winch safety shutoff switch
WO2006067555A1 (en) 2004-12-21 2006-06-29 Maquet Critical Care Ab Liquid dosing arrangement
US7487614B1 (en) * 2005-01-27 2009-02-10 Seth Walker Radio controlled gill net recovery transmitters
US20090133313A1 (en) * 2006-08-08 2009-05-28 Henning Skjold-Larsen Angle-Based Filling Ratio Indicator
US9968824B2 (en) 2006-08-10 2018-05-15 Exerciting, Llc Exercise device providing user defined pedal movements
US20090282723A1 (en) * 2006-08-31 2009-11-19 National University Corporation Tokyo University Of Marine Science And Technology Trawl net layer-by-layer collecting device
US8020336B2 (en) * 2006-08-31 2011-09-20 National University Corporation Tokyo University Of Marine Science And Technology Trawl net layer-by-layer collecting device
US20140373425A1 (en) * 2011-09-22 2014-12-25 Scantrawl As System and method for controlling and displaying parameters during trawling
US20150135835A1 (en) * 2012-05-16 2015-05-21 Scantrawl As Twin trawl geometry
US9877466B2 (en) * 2013-03-13 2018-01-30 Kalapa Bvba Fish-sorting system for sorting fish in a dragged fishing net
US20140259864A1 (en) * 2013-03-13 2014-09-18 Kalapa Bvba Fish-sorting system for sorting fish in a dragged fishing net
US20150156998A1 (en) * 2013-12-09 2015-06-11 Smart Catch LLC System, method, and platform for remote sensing and device manipulation in fishing environments
US20150272094A1 (en) * 2014-04-01 2015-10-01 Lawrence Ahlfert Pearlman "Smart" Semi-Autonomous Trawler Fishing Net
US11382318B2 (en) * 2017-07-24 2022-07-12 Stø Technology As System, apparatus, and method for trawl handling
EP4066634A1 (en) * 2021-03-23 2022-10-05 Volu Ventis ApS Controllable trawl doors and a method for controlling the same

Also Published As

Publication number Publication date
ES2182091T3 (es) 2003-03-01
NO962273L (no) 1997-12-04
EP0959676B1 (en) 2002-08-21
NO962273D0 (no) 1996-06-03
NZ333103A (en) 2000-03-27
AU3109097A (en) 1998-01-05
DE69714863D1 (de) 2002-09-26
PT959676E (pt) 2003-01-31
DK0959676T3 (da) 2002-12-02
NO302391B1 (no) 1998-03-02
IS4916A (is) 1998-12-03
EP0959676A1 (en) 1999-12-01
WO1997046087A1 (en) 1997-12-11
IS1879B (is) 2003-06-20

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